Jomonsugi Cedar
This immense and ancient tree may be the oldest Japanese cedar (Cryptomeria japonica) in the world. With a height of 25.3 meters and a trunk circumference of 16.4 meters, the Jomonsugi Cedar was once suspected to be two separate cedars that had fused together. However, DNA testing has since confirmed that it is a single tree.
The Jomonsugi Cedar is estimated to be between 2,000 to 7,200 years old, but it cannot be more precisely dated. Carbon-dating tests in 1984 proved the tree was at least 2,170 years old (±110 years). The upper limit of its age, however, is less certain. The tree’s inner core is hollow, so it is impossible to take samples of the oldest layers for tree-ring counting or carbon-dating. In addition, the trunk is too wide to allow non-invasive CT scanning to map its tree-ring patterns. Instead, researchers have used the known growth rates of Yakushima’s other giant cedars as well as information about ancient volcanic and climatic activity to narrow down the tree’s age. The eruption of a nearby undersea volcano destroyed most life on the island around 7,200 years ago, so the Jomonsugi Cedar is unlikely to be any older.
The Jomonsugi Cedar’s irregular shape made it unsuitable for timber, which ensured the tree survived the intense logging activities of the Edo period (1603–1867). Evidence of forestry activity in the area—such as the stumps of other felled cedars—confirms the giant tree was known to island residents at the time. At some point, however, its existence was apparently forgotten, because in 1966 the tree was “rediscovered” by Yakushima resident Iwakawa Teiji. Iwakawa named his find the “Oiwasugi” (the Great Iwa Cedar) after himself. The following year, a full-page article about the tree appeared in the regional Minaminippon shimbun newspaper. The headline used the term “Jomon,” in reference to Japan’s Jomon period (c. 14,500 BCE–300 BCE), to describe the tree’s age. Although Iwakawa continued to call the tree “Oiwasugi” until his death in 1987, “Jomonsugi Cedar” quickly caught on and has since become its official name.
In 1983, a poster campaign run by the Ministry of the Environment showed a local high school student posing next to the trunk of the ancient tree. These posters appeared in train stations and city halls around the country, and visitors to Yakushima began to increase. By 1990, roughly 10,000 people a year were making the climb to see the Jomonsugi Cedar. To minimize the erosion caused by so many hikers clambering around the tree’s roots, the first observation deck was built in 1996. By 2008, over 90,000 people per year were visiting the Jomonsugi Cedar.
The Jomonsugi Cedar is host to more than 10 species of epiphytes (plants that grow on rock surfaces or on other plants), including several varieties of rhododendron, Japanese star anise, Japanese rowan, and other cedars. In 2005, the weight of heavy snow brought down one of the ancient tree’s branches: a 5-meter-long, 1.2-metric-ton limb that was removed by helicopter. The branch is now on display at the Yakusugi Museum, where visitors can touch this piece of the island’s natural heritage.